The present invention relates to a mini disc system, and more particularly to a method for converting position data of a cluster and a sector of the mini disc into corresponding time data.
In a conventional mini disc system, a mini disc has storage clusters, which contain sectors. Further, addresses for the clusters and sectors are recorded on the mini disc, however, however, no corresponding time information is recorded on the mini disc. Although time information is not recorded on the mini disk, it is possible to provide a; user with corresponding time information by the mini disc system performing a conversion operation to convert the position information of the mini disc to time information. This is unlike a general Compact Disc (CD) which has time information recorded on a disc thereof. Therefore, in order to obtain time information for a mini disc, it is necessary to convert the mini disc address information into the corresponding time information.
In order to perform the address to time conversion, a conventional mini disc system employs a time table. The time table consists of cluster numbers each having a word length of 2 bytes. Because of this structure, a large amount of memory capacity is required and assigned to a microcomputer ROM, causing an increase in the required ROM storage. Therefore, in accordance with the increase of the size of the ROM, problems arise in which the cost per mini disc system becomes high and the program size of programs used in the microcomputer are limited.
FIG. 1 shows a block diagram of a conventional mini disc regenerating device.
A servo 9 is controlled to drive a feed motor 5 and a spindle motor 7 in response to a control signal from a system controller 27. A pick-up 3 reads a radio frequency (RF) signal from a rotating mini disc 1. An RF amplifier 11 amplifies the RF signal output from the pick-up 3 to a predetermined level. An Eight-to-Fourteen Modulation (EFM) and an Adaptive Cross Interleave Reed-Solomon Code (ACRIC) decoder 15, having a structure similar to a conventional CD signal processor, demodulates the output signal of the RF amplifier 11 and then stores the demodulated signal in memory 17 as digital data. The memory 17 is controlled by a Shock Resistance Memory Controller (SRMC) 19. The digital data, the cluster address consisting of one word, i.e., 2 bytes, and the sector address consisting of 1 byte, are included in the memory 17, respectively. Further, an error flag indicating whether or not the corresponding digital data is in error, is included in the digital data. The digital data stored in the memory 17 is output to an Adaptive Transform Acoustic Coding (ATRAC) decoder 21 by a sound group of 212 bytes via the SRMC 19 under the control of SRMC 19 receiving a data request signal from the ATRAC decoder 21. At this time, the error flag indicating whether or not the corresponding digital data is in error is also output with the digital data. The ATRAC decoder 21, applied via the SRMC 19, extends data of the sound group unit to the original data and then outputs the data to a digital/analog converter 23. When the digital data is applied to the ATRAC decoder 21, the cluster and sector addresses stored in memory 17 are output to system controller 27, e.g., a microprocessor, under the control of SRMC 19. The system controller 27 controls the servo controller 9, the EFM decoder 15, the SRMC 19, the ATRAC decoder 21, and a display/key input device 25.
FIG. 2 is a detailed structural view of system controller 27. An I/O interface 31 interfaces the address output from SRMC 19 and various data inputs and outputs between the EFM and ACRIC decoder 15 and ATRAC decoder 21 to a CPU 33. The CPU 33 controls a RAM 35, a ROM 37, and an Arithmetic and Logic unit (ALU) 39: Cluster and sector addresses applied via the SRMC 19 are stored in the RAM 35 by the CPU 33. These cluster addresses which consist of a word having 2 bytes, and sector addresses consisting of 1 byte, which are stored in RAM 35, are the same as the addresses stored in memory 17. The time tables which convert the address stored in RAM 35 into time information, are stored in ROM 37. The ALU 39 generates time information by adding the time unit information from the time tables stored in ROM 37, which effectively perform time conversion. An I/O interface 41 outputs the time information, which is added in the ALU 38 under the control of CPU 33, to display 25. Thus, the display 25 displays the current time information of the mini disc system.
FIG. 3 shows a flow chart of the conventional time conversion method which is performed within the system controller 27 of the mini disc regenerating device.
FIG. 4 shows a conventional time table chart formed based on cluster words, in ROM 37 of the system controller 27, for converting position data into time data.
FIG. 5 shows a time table chart formed based on sector bytes, in ROM 37 for converting position data into time data.
As shown in FIGS. 4 and 5, 3 bytes of data representing minute, second, and millisecond values that correspond to a particular mini disc cluster are stored in ROM 35. Further, 2 bytes of data representing second and millisecond values that correspond to a particular sector are also stored in ROM 35. The symbol H' shown in the time tables of FIGS. 4 and 5 indicates that the numeral following the symbol is represented as a hexadecimal number.
Referring to FIGS. 2, 3, 4, and 5, the conventional time conversion method of a mini disc is explained.
As shown in FIG. 4, CPU 33 detects the input cluster and sector addresses, or numbers, which are stored in RAM 35. In step 100 CPU 33 then converts the cluster numbers, which are represented by one cluster word that is 2 bytes long, which represent position information of the mini disc, to corresponding time information by using the time table based on cluster words and containing time entries which are stored in ROM 37. In other words, the conventional time table which is based on cluster words, is based on a full cluster word, i.e., 2 bytes, and hence contains data entries for each and every cluster of the mini disc. Further, in step 102, as shown in FIG. 5, CPU 33 converts the corresponding sector number within the cluster to time information by using the time table based on sector numbers and containing corresponding time entries. In step 104, ALU 39 of CPU 33 converts the position information of the mini disc to time information by adding the converted time of the cluster consisting of minutes, seconds, milliseconds generated in step 100, to the converted time of the sector number consisting of seconds and milliseconds generated in step 102. This converted time information is sent to display 25 through the I/O interface 41 for display.